Patent Literature 1 describes a device which alerts a vehicle driver who is inattentively driving a vehicle. More specifically, an image of a driver's face is captured by a camera and an orientation of a head and an orientation of eyes are found by image analysis to determine whether the driver is looking away on the basis of an analysis result.
The inventor conducted a study of using the alerting device described in Patent Literature 1 for inattentive driving caused by looking at a display device attached to an instrument panel in a vehicle interior, and discovered that the alerting device determines that the driver is looking at the display device when an orientation of the face and an orientation of the eyes are within a predetermined range set in advance. The predetermined range may be set empirically by actually finding an orientation of the eyes of the driver or the like.
In recent years, display contents of a mobile terminal, which is carried into the vehicle interior, become rich in variety. Thus, concern is arising about inattentive driving caused by looking at a display unit of the mobile terminal instead of the display device attached to the instrument panel of the vehicle. Moreover, a portion to which the mobile terminal is attached in the vehicle is not particularly specified, the predetermined range cannot be set to a fixed value as disclosed in Patent Literature 1. It is therefore difficult to determine whether the driver is looking at the mobile terminal.